High-power microwave (HPM) bombs that use an enormous electromagnetic radio pulse to disable computers, electronics, vehicles, guided missiles and communications while leaving people and structures unharmed have been under investigation in research labs for a number of years. Until recently these weapons have been impractically large at over 3.5 meters long, but researchers at Texas Tech University have now built a self powered device with U.S. Army funding that measures 15 cm in diameter and only 1.5 meters long, making it small enough to be considered portable.